Helicopter with auxiliary rotor



Oct. 14, 1952 c. G. PULLIN ETAL HELICOPTER WITH AUXILIARY ROTOR OriginalFiled Dec. 9, 1946 4 Sheets-Sheet l A TTORNE YS C. G. PULLlN ETALHELICOPTER WITH AUXILIARY ROTOR Original Filed Dec. 9, 1946 4 Sheets-Sheet 2 T. W M f M. M W

Oct. 14, 1952 c. ca. PULLIN EI'AL 3 33 HELICQPTER WITH AUXILIARY ROTORq/ wma A TTORNEYS (3. G. PULLlN EI'AL v HELICOPTER wrrn AUXILIARY ROTOROriginal Filed Dec 9, 1946 Oct. 14, 1952' 4 Sheets-Sheet 4 VgZfRSATTORNEYS name of the joint applicant Patented Oct. 14, 1952 UN TEDSTATES PATENT 7 2, 13,743 sntieertst W XiPIWBQt B .GyriI Georg, co leae' Billlin, Tadburn, Ampfield, and gel Shapiro, Hampstead, London,assignors', by mes k .0 hi'nany f America; Ph lade ph a; neqfnelawarew Qg a application December 9, 1946, Serial No.

7, 5,988; Divided and this application July Section -1,Piiblic--Law 690,August 8, 1946 :Bat'entQeXpircs September-Q37,

This invention relates l Q fieliqikptfifi Al i kind provided withan-auxiliary rot "ng a horizontal thrust, (situated at a distance {1pmth aircraftec. is. on he ton landkaiik eqi f line. its thrust beingutilized for compensating the torquerreaction of the main flitting otor'sys: tem.

This app i a i a dis-15101 pf le nli, Serial Number 714,988, which ,es di n he er in 7o, pac

ber 9, 1946.

We have found that the ,overall efiioien cy of a helicopter of this:kind can beimproved at the high-speed end of the fonward vspeedrange ifthe auxiliary rotor can be made ,to contribute substantially to .thepropulsion ,of the 'aircraft and its propulsive thrust ,ls progressivelyin? creased as thespeed is increasedgin theniedium and low-speed parts Iof the spe'ed range thebfest efliciency is obtained bylrelying entirely"on the main rotor systemforpropulsion ,as we'll fas sustentation, theauxilia rotor being' usedsolely for torque-reaction compensation andyawin control. The transition between the .mediumspeed" and "highspeed,parts of'the speedrange,

being the speed at whichit bvcomesiadvantaeous to begin obtainingpropulsive thrust tfroriilthe auxiliary rotorjwill depend qgsfiqesignparameters of individual aircraftj itz isnot in general very critical,but usually lies ne rerhe upper limit of the design,. speed.rang egthan. the lower-limit-(which is zero).

According to i riehtinvenfiw thae iary rotor is of the so-call edpaddlewheelltype, by which is meant;arotor with aroioil{shaped bladeswhose spanw-ise axes lie iinlpl'anes tettaining the axis ofrotationa dare symin meat ly spaced around it,-thebla "sillated about theirspanwise axes once olutidn'of the rotor, and the oscillations'lof' allthe-[blades being identically phased Qwith reierencj lto a datum, fi eth r s ec s-te armame- .I -Q a rotor will produce a thruserpendicular."to its axis and as usedin this-invention the! axis issubstantially ,vertical solthat:

sarily horizontal. V

. The inventionprovides for use of an auxiliary rotor of thecharacterabovereferred to, to-

gether with control means providing 1 tor variation of magnitude anddirection of; the thrust of the auxiliary rotor, whereby theauxiliaryrotor may serve not onlylfor controldnyaw, for instance forcompensatingrfor the torque-lreaction of the main liftingr rotorssystem,. butmay also serve to contribut propulsive effect.

5 tional flight; propulsiveefiectis ilerived 65 twecn argiritermediatenositio tszoa fi ,ra vabi 9 ttain-tea i to wv d a n- Ftrol n ean'spreferably 'interldcliedfwith other control organs ofthe'aircr'aft'sdthat when he normal controls are actuated to effectft" the auxiliaryrotor, at Qleastin the up e ncensed r n e iththe paddle wheel, type ofan" tid taste ess fli a 9 a, blade oscillation o any given 7 mph ridphase may be considered asthe resultant. of two inde e de os il a on odi fi i v i iv.

icon col;

a ei sc' aii h' imz rc led, olely .t i h mpfiitiide incr as prq iesswethelatter ex ee sapt .trol'. member..- displac.Bmene ls ilb-greaterthanis,required.tomaiiitairiAtroc ty .li Lthrustefor; positionsof ithc control ,piernber e'' ndin 1130 the transition speedandthe-limiting nosedown position.

tion. T'rhshen s rotates'fwith theme 4'2, m

and its forward end is closed by a non-rotary How the foregoing objectand advantages are 3 of a helicopter embodying the invention, Figure 1'showing the rear portion and Figure 1a the front portion of thehelicopter; l

Figure 2 is an end view of th auxiliary ro'tor;-

Figure 3 is a central vertical section 'of the auxiliary rotor takenalong the line 3-3 of Figure 2;

Figures 4 and 5 are partial sections weenie-i=1 spectively along thelines 4-4 and 5.5 v of thatif'piplonged they would all pass through aFigure 3;

Figure 6 is a central axial section of the lifting rotor hub and a bladearticulation, this view being on an enlarged scale as compared with Fi ue 1a; and

' Figure 7 is a plan view of the parts shown in Figure 6, to the samescale. In Figures 1 and la the helicopterhas a body I! enclosing anengine l8, on the front'of which is a main gearbox l6, from which atransmission shaft is taken to a lifting-rotor reduction-gear housing2|; and an upright shaft 22 transmits the engine powerfrom the rotorreduction gear 'to' the lifting-rotor hub 23 carrying rotor Pitchingdisplacement of a conventional control column 25 operatesa pitchingcontrol linkage hereinafter described, connected to a foreand-aft lever26 of a swash-plate mechanism for applying so-called cyclic pitchcontrol 'to the lifting rotor blades. Similarly a rolling controllinkage, operated by rolling displacement of the control column andcomprising a torque tube 21, crank 28, push-pull rods23, 3|, 33 and bell-cranks 30, 32'is connected to atransverse lever I6 of the swash-platemechanism (see Figure 7). g

plate 54 on which the shell 53 is located by a bearing55 a 4 Theamplitude and phasing of the oscillations of the blades 45 about theirspanwise axes, that aboutfthe' axes of their pivotal mountings 44, 43are varied'by displacing the shell 53 in a direction, perpendicular toits axis. Such a displacement will cause the rods 46'and the blades 45to which they are fixed to rock about their pivotal mountings 44,-' 435-:'the angular and linear displacements, of the rods relatively to theshell 53 On the rear of the engine is an. auxiliary gearcarriesblade-bearing brackets 43 rotatably supporting shafts 44 which areparallel to the" axis of the hub-shell and'rim, and on which the blades45 are cantilever-mounted. To each shaft'44 is secured a radial rod 46.v

The hub -shell 42Z-'is" integrally1formed 'tvith a I'hub -disc 42a,whose central boss houses the outer raceof a ball-type freewheelcoupling41; andthe inner race of this coupling is -carried byan internallytapered collar 48 keyed onto' 'thetaperend of shaft 31." 'The forwardend of the hubshell 42 is closed vby'aj'fixed plate 49formedwith a boss50 having 'a' central 'opening' constituting a steady bearing forthes'haft 31. 1

c The rods 46 passthroughopenings in the hubshell 42 and slide inballni'embers 5lwhich are pivotally supported in flanges'5 2integrally-formed on" an inner shell 53 and 'extending-from it inplane's perpendicular tofthe axis ofrotation... .The shell 53 hasopenings toiacconimodatethe-ends of rods 46 and the pivotal axes'on'wh'ich the members 5| can turn are parallel to the axisofrotabeingaccdminodated by the sliding and pivoting- 2 joints 5|. It canbe shown that if the shell 53 is 'so'adisplaced as to become eccentricwith the wheelAlLthe rods 46 are displaced in such a way pointeccentrically displaced in the same direction as the centr'e'ofthesh'ell 53, the distanceof this; point from the wheel centre beingproportional to the eccentricity of the shell 53; the ratioof-thes'edistances is the same as that of the radii of the pivotalconnections'44, 43 and 5| respectively, taken from the rotor centre.Such a disposition of the rods 46 brings about, when the rotor rotates,an oscillation of the rotor blades of satisfactory wave forin'i Toenable the" shell 53 'to -be trically from the hub 42, 42a, it isconnected to the hub plate '4 2d 'by an O ldh am type couplingand asimilar coupling connects the non-rotary locatin p13t'5 with-'-the fixedplate 49. The lat ter coupling co'ns'i'stsof an intermediate plate 56'iuwhich are formed two pairs'of slots 51, 58 located on mutuallyperpendicular diameters (see Figure 2}in whichtheplat'e 49 has beenremoved, and Figured}. -"Slots"51 are engaged by pins 59 fixed inplatens andf sl6ts'58 by pins 60 fixed in the locating-plate'-54.-"-Similarly the hub plate 42a'an'd the shell 53 Carry pairs of pins 65 62respectively located of; mutually perpendicular diametersandengaging-passer slots'63, 64 formed inan intermediate plate 65 (seeFigure 5).

Fore and'aftdisplacement of the shell 53 is effected by displacing theintermediate plate 56 in the tore-and aft; direction, the displacementbeing transmitted-by pins-66; for this purpose cables'66, 61, led'ove'rJockey-pulleys 68, aresecured to the edge of plate 56 at the front andrear respectively. Fore and aft displacement of shell 53 causing acorresponding displacement'of the meetingpointf of rods "46, gives riseto a blade oscillation'inthe-appropriate phase for produc -ingiatransverse thrust whose direction is determined by'the direction"(forwards or rearwards) of the eccentricity of tlie rod-meeting pointand b the" directionofrotation of the" auxiliary rotor (see Figures z',3 and 4).

Similarly'tr'a 'ver'se' displacement-of the shell 53 giving a fore an'cl'aftthrus't component is effected by'the-jcable'ffis; whose en'ds 69d,69b are connected tothe 'edge o'f the locating plate 54 at port andstarboard" respectively (see;Figures'2 and4). c

The cables 66, 61 areledover jockey pulleys 13 direct to the rudder'pedals 'il, 12; and the cable 69 is led over jockey-pulleys 13 to thepulley 14 (see Figure 1a). f

When the locating. and intermediate plates 54, 56 and shell 53 areconcentric with the auxiliary rotor thelatter rotates idly. and deliversno thrust provided there is no relative Wind perpendicular to the axis.Eccentric di'spl'ac'ementof the shell 53 causes the rotor blades to beoscillated about displaced eccen their spanwise axes, once perrevolution, with an angular amplitude 'proportional to the extent of'theeccentricity of the-shell 53. The phasing of the oscillation is suchthat the maximum excursions of thebl'adesfr'om their neutralpositionoccur in a plane perpendicular to the'eccen' tricity'of theshell 53, 'and'the maximum excursion ofthe bladeileadin'g edge towardsthe axis of rotationoccurs 90 in advanceof the direction inwhich'theshell 53 is eccentrically displaced, with reference to thedirection of rotation. If there is no relative wind in the plane of themaximum excursionsof the blades, the thrust component in this plane actsfrom the side on which the excursion of the blade leading edge istowards the axis and towardsthe side where the leading edge excursionisa'way from the axis. In a relative wind zero thrustiis-obtained with ablade oscillation such that the leading edge is remote from the axis inthe upstream position,

the amplitude of the oscillation being proportiomal to the relative windvelocity. If the amplitude is increased beyond thatneeded to give fzerothrust the thrust acts in the downwind direction. Thus in this examplein which the auxiliaryj'rotor is left-handed (as viewed from above) the'-maximum excursion of the blade leading edgestowards the axis occurs onthe starboard side of the rotor'when the shell 53 is displaced .rear-'wardly; and consequently the thrust is to port.

Similarly displacement of the shell 53 forwards causes a thrust tostarboard. To maintain zero thrust in the fore and aft direction, theshell 53 must be displaced to port progressively with increasing forwardspeed, and to obtain propulsive thrust the displacement to port must befurther increased.

The elements of the lifting rotor shown in Figures 6 and '7 comprise thedriving shaft 22 and the hub 28 on which blade root stubs 15 arearticulated by drag pivots 16 and flapping pivots 11; and the blades 24are supported by the stubs 15 on torsional or blade-pitch-varyingbearings 18. The driving shaft 22 is integral with the hub 23 and issupported in bearings 19, 80 by a cylindrical housing 81 secured to apylon structure 82.

Pitch variation of the rotor blades, both mean and.cyclic, is effectedby a swash-plate mechanism comprising a collar 83, which slides on theoutside of the housing- 8|, being prevented from rotating by a splinedconnection 84, and which has a male spherical surface 85 engaged by acor responding female spherical surface of a nonrotating swash-platemember 88-, the latter being prevented from rotating by a pin-and-slotconnection 81. The member 88 carries a rotary swash-plate ring 83 on abearing 89 and the ring 88 is rotated by shaft 22 through a connectionconventionally represented by an arm 90 integral with the ring 88engaged by an arm 9| rigid with the shaft 22. Arms 92 projecting fromthe ring 88 are connected witharms 93, secured to the blades 24 bystraps 94, through links 95 with ball-joints 98, 91 at each end.

Cyclic pitch variation is efiected by the arms 26 and I6 connected tothe pitching and rolling control circuits respectively, these arms '26and 18 being rigid with the non-rotary swash-plate member 86.

Variation of the mean rotor-blade-pitch angle is effected by shiftingthe collar 83 vertically on tion through a universal joint with apush-pull rod 99.

, shaft hf lever-'1 00 and" over a The control circuit operating the arm98 is shown in Figurela, and comprises'the rod 99,

en a mmen e m;

Referring further to l Figtiie 1 *the pitching controljcircuit whichoperates the swash plate arm 2t" for tilting; the swashgplat jseg- 8-8in the pply hscyciic pitch pitching plane and thereby .r a e; p is P punrods? 184 ,{105} s" bellcranks 101, u us.- This control circuit isconnected to nearm [09a of {a three-armed bell-"crank "it ii 917;; IBet; to Whose lower 4 arm {I 09- f and a'ft'f motion fof the 'ttebyaidus'h-pull The third mrloav of-thejb max ma med,

mat seems-ates 'by'ja ptsn-p rise- 1- u with a lever i l' 2 {which cpe'atesthe they '14. r The ililey 14- carries the cableftreviouslyf-nientioned, which operates "the variable pitch n echanismthet'au'xiliary rotonf" Themutua'l relationship "of thecrank a rms I89,ma, 189i) is s'u'chthat when thecontro eal- {isin -a rearward positionappropriate to hovering the arm lflsbais dead-centered "and movement ofthe control column has no effectdisplacement in the pitching plane tocontrol 8 member displacement progressively decreases and the ratio ofauxiliary rotor pitch changeto control member displacement increasesprogressively. The connection to the auxiliary rotor variable pitchmechanism is so made that the auxiliary rotor pitch is coarsened as thecontrol 001- I umn is displaced forwardly and the control circuits areso proportioned that the auxiliary rotor pitch is coarsened sufiicientlyas the control column approaches its fully forward position to cause thepropulsive thrust of the auxiliary rotor to increase progressively.

It will be noted that the control of the auxiliary rotor in respect toits propulsive function, is effected by the control column 25 and thatthe propulsive thrust of the auxiliary rotor is thereby coordinated withthe pitching control of the lifting rotor, throughout the whole forwardspeed range; and further that the yawing control system is unusuallysimple.

We claim:

1. A helicopter having a lifting rotor system with means forcontrollably displacing the lift vector in the pitching plane of theaircraft and an auxiliary rotor comprising a series of blades with theirspanwise axes paralleling the rotational axis of the auxiliary rotor,and with the latter axis positioned substantially vertically and offsetfrom the center of gravity of the aircraft and with its blades mountedfor oscillation about their spanwise axes, independent controlmechanisms for varying the amplitude of oscillation of the paddle-wheelrotor blades about their span axes in each of two phases whose maxima ofangular blade displacement from the mean position in either sense occurrespectively in the fore and aft and transverse vertical planes, themechanism controlling the amplitude in the fore and aft r l Ffirum ormed'b r f e fih v 7 system to eflect variation of said last mentionedamp-lituda 'the couplin connection pr ovidi ng for progressive increaseof said last mentioned amplitude as said member is displaced in thenose-downfdirection, and the mechanism controlling the amplitude -o f,bl aide oscillation in the transversephase being operated by anindependent control member for controlling the aircraft in yaw. r v

2.. A helicopter havingalifting' rotor system and having afight controlfor the lifting rotor system for eiifecting translational flight, I anauxv iliary rotor comprising a series of blades with their spanwise axesparalleling I the rotational axis of the auxiliary'rotor, and with thelatter axis positioned substantially vertically and-offset from thecenter of gravity of the aircraft to'provide for controlof the aircraftin-yaw, and having blades *mounted for oscillation about their span-wiseaxes, control mechanism for varying the amplitude of oscillation of theblades in a fore and aft plane, and meansvin'terconnecting saidmechanism with'the said flight control of the" lifting rotor systemvofthe aircraft and said mechanism including interconnections providingforauxiliary rotor blade oscillation in aplane to I, CYEILIGEORGEPULLIN.

, JA'COB SAMUEL SHAPIRO.

' REFERENCES CITED The following references are of record in the file-ofthis patent:

UNITED STATES PATENTS Number Name Date 1,681,500 Y Schneider Aug. 21,1928 1,870,674 Ehrha'rt Aug. 9, 1932 2,123,916 Rohrbach July 19, 19382,364,096 Platt Dec..5, 1944 2,364,496 Vogel Dec. 5, 1944 2,385,889Skavinsky Oct. 2, 1945

